This document provides an overview of cell membrane structures and functions. It discusses how membranes form fluid compartments that act as barriers while also regulating exchange. The membrane is made up of a phospholipid bilayer with integral and peripheral proteins. Transport proteins such as channels, carriers, and receptors facilitate movement of substances across the membrane. Structural proteins anchor the cytoskeleton and provide cell polarity, while carbohydrates form an external glycocalyx layer. In summary, the document outlines the key components and functions of the cell membrane, including its role in compartmentalization, transport, and communication.